This invention relates to a method for making a semiconductor package that includes stacking a conventional lead frame and semiconductor die sub-assembly with a patterned sheet of an insulating material and a metal heat spreading block, and bonding the stack of components together.
Methods for the mass production of semiconductor packages with few exceptions include automatically mounting semiconductor die on the die attach pads of lead frames and by automatically connecting the terminals or terminal pads of the die to lead fingers of the lead frame by fine wires.
However, when a heat spreader block is to be included in the package it has heretofore been found necessary to deviate from the standard methods for making the die to lead frame sub-assembly and thus additional tooling has been required to manufacture such prior art packages incorporating a heat spreader.
It is therefore an object of this invention to provide a method in which mass produced die to lead frame sub-assemblies are incorporated in a semiconductor package including a heat spreader thermally intimate with the lead frame.
It is yet another object of this invention to provide such a method amenable to mass production using standard production lead frames, standard lead frame to die sub-assemblies and standard lead frame handling machines, parts-picking and placing machines.
It is a further object of this invention to provide such a method in which the distal ends of the lead frame fingers and the lead frame die attach pad are uniformly and repeatably connected thermally but may be insulated electrically from a heat spreader block.
It is another object of this invention to provide such a method in which a different insulating medium is employed for insulating of the lead frame finger ends than is used for insulating the die attach pad from the heat spreader block to afford versatility in thermal design of the semiconductor package.